In this courtroom sketch, U.S. Army Maj. Nidal Malik Hasan is shown during closing arguments of his court martial in Fort Hood, Texas. / Brigitte Woosley AP

by Rick Jervis and Doug Stanglin, USA TODAY

by Rick Jervis and Doug Stanglin, USA TODAY

Maj. Nidal Hasan, the radicalized Army psychiatrist who turned his gun on fellow soldiers at Fort Hood four years ago in the name of jihad, was found guilty Friday of all counts, including premeditated murder.

He now faces the death penalty and could be the first person the U.S. military puts to death in more than 50 years.

A 13-member panel, or jury, of high-ranking officers voted unanimously to convict Hasan, 42, on a slew of premeditated murder and attempted murder charges for killing 13 people and injuring 31 others in the Nov. 5, 2009, attack at the U.S. Army base in Texas.

As the verdict was read, Hasan had no visible reaction.

Nor was there any outcry from the audience, which included relatives of the victims. Military judge Col. Tara Osborn had warned against any outbursts.

Several family members, however, left the courtroom with tears in their eyes.

The panel, which took only about seven hours to convict Hasan, now turns to the sentencing phase of the trial to decide whether to recommend putting him to death by lethal injection or have him spend the rest of his life in prison. Prosecutors are expected to call 16 witnesses over two days during the sentencing phase.

The 17-day court-martial of Hasan included 89 prosecution witnesses who described in vivid and graphic detail how Hasan entered a medical processing building on Nov. 5, 2009, and opened fire on unarmed soldiers and one civilian with a FN 5.7 semiautomatic handgun, reloading high-capacity magazines several times and firing 146 rounds.

Hasan, a Virginia-born Muslim who represented himself, was mostly passive throughout the trial, cross-examining only a handful of witnesses, calling none himself and opting not to make a closing statement. From his opening statement Aug. 6, he admitted to being the gunman and pledged his allegiance to the mujahideen, or holy warriors.

The case had been besieged by delays and bizarre twists, including the dismissal of the original judge during a dispute over to allow Hasan to grow a beard. Hasan also fired his defense team and chose to represent himself.

He did not call witnesses or testify, and he questioned only three of the prosecutors' witnesses.

Through media leaks and statements to the judge, the American-born Muslim signaled that he believed the attack was justified as a way to protect Islamic and Taliban leaders from U.S. forces in Afghanistan and Iraq.

In closing statements Thursday, military prosecutors painted a picture of Hasan as a disgruntled and radicalized American-born Muslim who became increasingly incensed at America's wars abroad and his own pending deployment to Afghanistan.

Through witness testimony, 911 calls and FBI videos, prosecutors recounted how Hasan purchased the murder weapon months before the shooting, spent weeks training to shoot at silhouette targets at a local shooting range and planned the attack inside busy Building 42003, where soldiers gathered for final medical clearance before deployments to Iraq and Afghanistan.

"The accused went out that day to kill as many soldiers as he could â?¦ or anybody else who tried to stop him," prosecutor Col. Steve Henricks said.

Several things pointed to a premeditated act, including paper towels Hasan placed between the 16 loaded high-capacity magazines he carried in his pants cargo pockets to keep them from clanking together and how he carried out the attack on the same day members of his unit were inside the building, Henricks said.

"The accused, without a doubt, held a premeditated design to kill," he said.

The U.S. military carried out its last execution on 1961, with the hanging of Army Pvt. John A. Bennett. He was convicted in 1955 of the rape and attempted murder of an 11-year-old Austrian girl.